Field of the Invention
This invention relates, in general, to holders and, in particular, to a new and useful holder for capillary tubes and phial holders.
The invention refers particularly to a phial or vial for holding capillary tubes that are intended for use with biomedical test instruments and in particular for certain blood tests requiring the counting of cells present in suitably diluted blood. This is particularly but not exclusively, for the counting of thrombocytes or platelets. The basic concept of the present capillary tube holder involves the evaluation of the difference of electrical characteristics which occur within the capillary port or hole upon the passage of a body contained in the sample that is to be counted. The main problem is that of avoiding or at least limiting the error which may occur upon a possible passage of an already counted body--and which has therefore already passed through the capillary tube--in the vicinity of the same capillary tube, which event may cause an electrical signal corresponding to that taking place upon a passage of a body and, hence, may lead to a mistaken count of a further particle.
According to the invention, the phial for holding capillary tubes, or capillary tube holder, is internally subdivided into an external chamber having an annular cross-section and an internal chamber having a circular cross-section most coaxial therewith. The outer wall of the chamber, which has an annular cross-section, carries the capillary port or hole and the inner tubular wall separating the two chambers has a hole disposed in alignment with that of the external capillary hole. The inner hole has a larger diameter than the outer capillary hole. Through suction, the sample liquid is made to enter inside the test tube of the platelet counter through the capillary hole. Soon after its transit into the capillary hole, the sample liquid goes through the annular hollow space and passes through the hole of large diameter, into the tubular inner wall to reach the internal chamber. Inside the hollow space having the annular cross-section, a slight call flow is thus generated through the hole of the tubular inner wall, said flow causing a fast removal of the sample liquid that has gone through the capillary hole with no backward flows in the direction of the outer capillary hole but with relatively very fast transit within the internal chamber defined by the tubular wall and having circular cross-section.
Advantageously, the inner tubular wall is coaxial with the wall of the test tube or phial holding the capillary hole, and the two chambers are widely in communication to each other in their upper parts where the suction takes place.
For the periodic washing, two pipes for the intake at a washing liquid are advantageously provided, one of which reaches the lower part of the hollow space having annular cross-section, while the other reaches the lower part of the internal chamber formed by the tubular wall.
The various features of novelty which characterize the invention are pointed with particularity in the claims anexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects obtained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.